/usr/include/crystalspace-2.0/csgfx/ is in libcrystalspace-dev 2.0+dfsg-1build1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/crystalspace-2.0/csgfx/bakekeycolor.h
/usr/include/crystalspace-2.0/csgfx/gradient.h
/usr/include/crystalspace-2.0/csgfx/imageautoconvert.h
/usr/include/crystalspace-2.0/csgfx/imagebase.h
/usr/include/crystalspace-2.0/csgfx/imagecubemapmaker.h
/usr/include/crystalspace-2.0/csgfx/imagemanipulate.h
/usr/include/crystalspace-2.0/csgfx/imagememory.h
/usr/include/crystalspace-2.0/csgfx/imagetools.h
/usr/include/crystalspace-2.0/csgfx/imagevolumemaker.h
/usr/include/crystalspace-2.0/csgfx/inv_cmap.h
/usr/include/crystalspace-2.0/csgfx/lightsvcache.h
/usr/include/crystalspace-2.0/csgfx/normalmaptools.h
/usr/include/crystalspace-2.0/csgfx/packrgb.h
/usr/include/crystalspace-2.0/csgfx/quantize.h
/usr/include/crystalspace-2.0/csgfx/renderbuffer.h
/usr/include/crystalspace-2.0/csgfx/rgbpixel.h
/usr/include/crystalspace-2.0/csgfx/shaderexp.h
/usr/include/crystalspace-2.0/csgfx/shaderexpaccessor.h
/usr/include/crystalspace-2.0/csgfx/shadervar.h
/usr/include/crystalspace-2.0/csgfx/shadervararrayhelper.h
/usr/include/crystalspace-2.0/csgfx/shadervarblockalloc.h
/usr/include/crystalspace-2.0/csgfx/shadervarcontext.h
/usr/include/crystalspace-2.0/csgfx/shadervarframeholder.h
/usr/include/crystalspace-2.0/csgfx/shadervarnameparser.h
/usr/include/crystalspace-2.0/csgfx/textureformatstrings.h
/usr/include/crystalspace-2.0/csgfx/trianglestream.h
/usr/include/crystalspace-2.0/csgfx/vertexlight.h
/usr/include/crystalspace-2.0/csgfx/vertexlistwalker.h
/usr/include/crystalspace-2.0/csgfx/xorpat.h